The present invention relates to a moving coil type cartridge hereinafter referred to as an "MC type". More particularly, it relates to an electrical signal generating structure for an MC type phono cartridge.
In an MC type phono cartridge, a pair of moving coils connected to a cantilever are disposed in a predetermined magnetic field defined by a magnet and a pair of pole pieces so that a voltage induced by the movement of the cantilever can be picked up as an electric signal.
The output voltage of a phono cartridge of the above-described MC type is low in comparison with other magnetic phono cartridges such as a moving magnet type cartridge. Since in an MC cartridge the moving coils are directly connected to the cantilever, it is very difficult to interchange styli or needles. Moreover, the assembly of such a cartridge requires much skill and manual dexterity. The MC cartridge assembly is thus time-consuming making it unsuitable for mass production and accordingly, expensive. Although the MC cartridge possesses such disadvantages, it is widely used especially in top class equipment because of its extreme high-fidelity.
Various different MC cartridges have been proposed. In most of these, paired pole pieces are employed to form the magnetic fields as described above. For this reason, the total weight of the cartridge is disadvantageously large. In addition, most MC cartridges require moving coils which are precisely machined so as to enhance the voltage induction efficiency. Such moving coils are difficult to produce.
It is thus an object of the present invention to provide an MC type photo cartridge whose construction is simple, whose voltage induction efficiency is high, in which stylus interchange is easy, and which is easy to assembly.